The Research Of Laser-electromagnetic Field Coupling Strengthening Improving Hardness And Wear Resistance Properties Of 45 Steel

45 steel is a kind of medium carbon steel with low price,which has good mechanical properties by proper heat treatment.As modern machinery develop into high speed and intellectualization orientation,machinery have high demands on material properties.Traditional heat treatment processing could not meet strict requirements of machinery on parts.To get high hardness and good wear resistance of modified surface layer and maintain excellent mechanical properties of 45 steel,45 steel was usually treated by surface hardening treatment.Laser transformation hardening processing of 45 steel was taken into optimization by the combination of numerical stimulation and experiment research in this paper and its inner principle of properties improvement was studied.The quenched sample was researched to eliminate disadvantage of laser quenching processing by doing magnetic treatment experiments.Temperature field of the specimen was researched by finite element software ANSYS and inner principle of hardening layer's properties improvement was revealed.The influence of laser power and scanning speed on the micro-structure was discussed by single factor analysis method.Experiment results indicated that laser processing parameters had great influence on microstructure and properties of hardened layer.The deep and width of hardened layer increased with laser power increasing,declined with scanning velocity increasing.The hardness of hardened layer increased first and then decreased with laser power and scanning velocity increasing.The influence of different laser scanning processing on hardness and wear resistance of 45 steel was taken into consideration.Surface hardness was tested by HR-150 A sclerometer.The wear loss of specimen was measured by electronic analytical balance.The topography characteristics of specimen after wearing was photographed by scanning electron microscope.Experiment results showed that hardness of modified surface layer increased first and then decreased with laser power and scanning velocity increasing.Wear resistance properties of specimen were improved a lot after laser quenching.Wear loss of specimen was reduced significantly and wear surface topography became more flat after laser quenching.The 45 steel which was under the process of laser transformation hardening was magnetized by self-made magnetic enforcement device.The effect of magnetic frequency,magnetic time on hardness and wear resistance of 45 steel was researched.Experiment results showed that surface hardness of 45 steel samples was all improved under proper magnetic processing parameters.A part of retained austenite was transformed into martensite because of decreasing of martensite activation energy when rotating magnetic field was applied.Microstructure of the sample was more compact.Wear resistance was improved.Considering the micro-crack happening during laser quenching process,stress field of the specimen was taken into numerical stimulation by finite element software ANSYS and stress distribution law of it was analyzed.The mechanism of crack happening was taken into research.Surface hardening treatment of 45 steel was processed by the way of laser transformation hardening coupled rotating magnetic field processing.The influence of rotating magnetic field on microstructure and wear resistance was investigated.Results indicated that thermal stress on the scanning direction was the main reason which could caused microcrack in the hardening layer.Microcrack of the hardening layer was significantly reduced;Microstructure of the hardening layer was refined;Microhardness and wear resistance of the sample were improved a lot after applying rotating magnetic field in the process of laser transformation hardening.